Ferroelectric Film Seed Layer for Semiconductor Bonding
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Solution Overview
Problem
Conventional semiconductor devices with ferroelectric films face limitations in enhancing characteristics such as bonding strength and crystallization, leading to potential peeling issues and decreased performance.
Innovation Solution
Incorporating a first seed layer with materials from both the ferroelectric film and conductive film, such as titanium and oxygen, between the ferroelectric film and the conductive film, to promote crystallization and enhance bonding strength, along with a stress film and sidewall insulating films to apply stress and reduce peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ferroelectric film is formed by crystallizing a high-k film in an amorphous state including hafnium by heat treatment, then the ferroelectric memory can operate at low voltages, but the bonding strength is insufficient and peeling occurs
Solution Approach 1:
A seed layer comprising titanium and oxygen is introduced as an intermediary between the ferroelectric film and the underlying layer. This seed layer acts as a mediator that enhances adhesion and prevents peeling, resolving the contradiction between maintaining low-voltage operation and improving bonding strength.
Solution Approach 2:
The seed layer is formed as a composite material containing titanium and oxygen in specific proportions (titanium concentration of 5-50 at%, oxygen concentration of 50-95 at%). This composite structure provides both strong bonding capability and ferroelectric compatibility, preventing peeling while maintaining device functionality.
2Reliability
If heat treatment is performed to crystallize the high-k film, then ferroelectric characteristics are achieved, but crystallization is insufficient and performance decreases
Solution Approach 1:
The seed layer comprising titanium and oxygen is formed in advance before the heat treatment that crystallizes the ferroelectric film. This preliminary action prepares the interface structure to facilitate subsequent crystallization, ensuring high-quality ferroelectric characteristics while preventing degradation during the heat treatment process.
Solution Approach 2:
The seed layer's specific compositional parameters (titanium concentration of 5-50 at%, oxygen concentration of 50-95 at%) are optimized to control the crystallization process. By adjusting these parameters, the heat treatment achieves sufficient crystallization for ferroelectric operation while maintaining structural integrity and preventing performance degradation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The enhanced bonding and crystallization improve the semiconductor device's characteristics by reducing peeling and maintaining performance, allowing for stronger intermolecular forces and effective voltage application during operations like write and erase states.
Implementation Method 1
performing a heat treatment at a first temperature to the amorphous film and the conductive film to form a seed layer between the amorphous film and the conductive film
Implementation Method 2
after performing the heat treatment at the first temperature, performing a heat treatment at a second temperature higher than the first temperature to the amorphous film to form a ferroelectric film
Data Source
AI summary
A semiconductor device includes a semiconductor substrate, an insulating film, a ferroelectric film, a first seed layer and a control gate electrode. The semiconductor substrate includes a source region and a drain region which are formed on a main surface of the semiconductor substrate. The insulating film is formed on the main surface of the semiconductor substrate such that the insulating film is positioned between the source region and the drain region in a plan view. The ferroelectric film is formed on the insulating film and includes hafnium and oxygen. The first seed layer is formed on the ferroelectric film. The control gate electrode is formed on the ferroelectric film. A material of the first seed layer includes at least one material of the ferroelectric film and at least one material of the first conductive film.